title: Accuracy of stop-cursor method for determining systolic and pulse pressure variation.
abstract: BACKGROUND
  Functional hemodynamic indicators (systolic pressure variation [SPV and SPV%] and pulse pressure variation [PPV%]) are sensitive and specific indicators of fluid responsiveness. It was unknown if these indicators could be accurately measured directly from the bedside monitor.
  
  
  OBJECTIVE
  Determine the accuracy of SPV, SPV%, and PPV% measurements by using a stop-cursor method compared with a digitized analog strip (gold standard).
  
  
  METHODS
  A prospective observational study using a convenience sample of 30 adult patients in a medical-surgical intensive care unit who were receiving mechanical ventilation and had no spontaneous breaths during 3 sequential ventilator breaths and had an optimized arterial catheter. The peak and nadir arterial pressure values for a ventilator cycle were simultaneously obtained by using the stop-cursor method on the bedside monitor and a hardcopy strip. The indicators were averaged over 3 breaths, and the difference between methods was calculated.
  
  
  RESULTS
  Data were analyzed from 29 patients (1 patient excluded) on assist control ventilation (mean [SD] for tidal volume, 7.5 [2] mL/kg; positive end-expiratory pressure, 7 [4] cm H2O). For SPV, the mean bias was 0.4 (SD, 0.9) mm Hg (95% limits of agreement [LOA], -1.4 to 2.2 mm Hg); for SPV%, 0.3 (SD, 0.9; 95% LOA, -1.5% to 2.1%); for PPV%, 1.0 (SD, 3.3; 95% LOA, -5.5% to 7.5%). In only 1 case (PPV%) was there disagreement on fluid response characterization.
  
  
  CONCLUSIONS
  Statistically significant small differences in SPV and SPV% were detected. The differences in SPV, SPV%, and PPV% were not clinically significant, suggesting that functional hemodynamic indicators can be obtained accurately with the stop-cursor method.
authors.affiliation: University of Washington Medical Center, Seattle, USA.
authors.forename: Laurel
authors.initials: L
authors.lastname: Tyler
authors.forename: Sheryl
authors.initials: S
authors.lastname: Greco
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Bridges
authors.forename: Sarah
authors.initials: S
authors.lastname: Barnes
authors.forename: Laura
authors.initials: L
authors.lastname: Brown
authors.forename: Kellie Garth
authors.initials: KG
authors.lastname: Green
authors.forename: Diane
authors.initials: D
authors.lastname: Wolfson
mesh_terms: D062186:Arterial Pressure; D001794:Blood Pressure; D006439:Hemodynamics; D006801:Humans; D007362:Intensive Care Units; D008991:Monitoring, Physiologic / Q000379:methods*; D011175:Positive-Pressure Respiration / Q000379:methods; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000379:methods*